With at least six classmates pregnant, including the valedictorian with her second child, it was clear to a handful of girls that Mission High School needed more information on safe sex. So the four students at this school deep in South Texas along the Mexican border — where the teen pregnancy rate is among the highest in the nation — decided they could help send the message by making their own movie. Two years later, the 16-minute educational film promoting condom use is available to public schools around the state. The movie, named "Toothpaste" in reference to a teen code...